How To Refill A Combi Boiler

This guide is specifically for refilling combi boilers.  Depending on your boiler type, the process may vary.

What You'll Need:

  • Locate your pressure gauge. It's usually a round dial on your boiler.
  • Find the filling loop. This should be two blue taps near the bottom of your boiler.


  1. Check the Pressure Gauge:  Take a look at your pressure gauge. If the needle is pointing close to zero, your system needs repressurising.  Ideally, the pressure should be between 1 and 1.2 bar (shown on the gauge).
  2. Locate the Filling Loop: Find the two blue taps on the filling loop near the bottom of your boiler.
  3. Turn on the Filling Tap (One Tap Partially):   There are two taps, but we'll only partially open one at first. Turn the tap closest to you slightly towards you, just enough to create a small opening.
  4. Open the Other Tap Slowly: While the first tap is slightly open,  use your other hand to slowly turn the second tap towards the wall (opposite you). You'll hear water filling the system.
  5. Monitor the Pressure Gauge: Keep an eye on the pressure gauge as the water fills the system. Once the pressure reaches between 1 and 1.2 bar, it's time to stop.
  6. Turn off the Taps: With the pressure between 1 and 1.2 bar, turn off both taps. Close the second tap first (the one you turned towards the wall), then the first tap (the one you opened slightly).

Congratulations! You've successfully refilled your combi boiler. Now you can enjoy a warm and cozy home.

Safety Note: If you're uncomfortable performing these steps yourself, or if you have any leaks, it's always best to consult a qualified heating engineer.

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